21 Nov 2012

Science and art often go hand
in hand. M.C. Escher played with geometry in his famous prints of impossible
realities, and anatomist Gunther von Hagenst captivated millions of people with
a display of preserved human corpses and body parts. More recently, a popularinstallationat the London Barbican Gallery offers art lovers
the unique experience of walking in the rain without getting wet.

Science lets art push boundaries, and so is
increasingly used by modern artists to shock and awe. But this is a two way
street.

Researchers from the University of Electronic
Science and Technology in China have now used recordings from brain scans to
create music, and they hope that listening to the brain will give new insights
into how it works.

EEG-fMRI music from two subjects (Credit: Lu et al 2012 PLoS ONE)

This unusual way of blending science and art was
first introduced in 1965 by the American composer Alvin Lucier in the pieceMusic for Solo Performer, but
it was not until the 1990s that 'brainwave music' boomed with the development
of powerful computers. Scientists and musicians now use computational models to
convert data from brain scan technology into music played by electronic
synthesizers.

In the new study published inPLoS ONE, Jing
Lu and colleagues developed a new method to combine readings from
electroencephalograms (EEGs) and functional MRI (fMRI) brain scans to produce
music that better mimics contemporary classical music. The amplitude and the
frequency of the EEG signal were used to create the pitch and the duration of
each musical note. This was then remixed with an fMRI signal, which set the
intensity of the notes played.

Functional MRI imaging (Credit: Wikipedia)

The authors acknowledge that the sources of the
two signals are however unrelated. "There is something a little arbitrary
about putting EEG and fMRI together in this way" says philosopher Dan
Lloyd from Trinity College, Connecticut, who was the first person to createmusic from fMRI scans. "But you have to start
somewhere, learning scales before you play a sonata, and this is a good
start" he adds.

EEGs measure the electrical activity of the
brain. Brain cells, or neurons, communicate with one another through electrical
signals. During an EEG, electrodes are attached to the scalp and plugged into a
computer that converts the electrical signals to waves. EEGs are currently used
to diagnose epilepsy and sleep disorders for instance.

fMRI, or functional magnetic resonance imaging,
on the other hand measures brain activity by detecting changes in blood flow,
and is mostly used in research. Neurons need oxygen to make energy, so when a
brain area is more active, oxygen-rich blood surges. The pattern of brain
activity across the brain is then represented in a color code.

The authors of the study plan to improve their
EEG-fMRI method so it may be used for clinical diagnosis, for example, if the
music could produce audible differences between healthy and sick brains. Lloyd
says

"With the proper sonification [conversion
to sound], something like a 'brain stethoscope' could be developed as a
clinical tool for detecting clues to a variety of brain conditions".

But there are skeptics. David Sulzer, a
neurophysiologist at Columbia University and jazz musician, thinks that
brainwave music can only detect very significant changes in brain activity,
such as an epileptic seizure. He says "If you cannot diagnose an illness
through a chart recorder readout, I do not understand how it can be done
sonically".

Sulzer believes music made from brain activity
is an art and a science didactic tool. For instance, he usesThe Brainwave Music Projectto teach the public about brain function before
his performances of brainwave music.

Whether brainwave music will be useful for
science or medicine remains an open question, but it can surely be said
that it has become an art form of its own. It might not be for everyone's taste
but brainwave music certainly causes an impression, which is the very
definition of modern art.

20 Nov 2012

At the bottom of the
ocean, there is a strange world of microbes thriving in mud sediments. They all
strive toward the same vital goal of using oxygen and available nutrients to
produce energy for growth, so competition is fierce.

The bacteria on the seabed
surface are the lucky ones, as they can readily take up oxygen from sea water.
But a couple of centimeters below oxygen is scarce, and bacteria buried deep
into the mud need to come up with more ingenious ways to gain energy.

In a new study published in Nature, a research team led by Nils Risgaard-Petersen and Lars Nielsen
at Aarhus University in Denmark, shows how some bizarre bacteria employ a
cunning trick to both feed from nutrients in deep marine sediment and consume
oxygen at the surface: they function as living electric cables.

A couple of years ago, the team made the astonishing discovery that electric
currents linked oxygen consumption at the top sediment layers with hydrogen
sulfide at the bottom, more than a centimeter away. "The identity of the electron
conductor has however been an enigma" Risgaard-Petersen says.

The scientists postulated
that bacteria could work together to conduct these electric currents through a
network of tiny hair-like appendages called nanowires. However, evidence so far
shows that bacterial nanowires can only transfer electrons over shorter
distances, so this alone could not explain the intriguing results.

To solve this riddle,
Risgaard-Petersen and colleagues collected samples of marine sediment from
Aarhus bay and carefully scrutinized the top sediment layers. In a true eureka
moment, they found tufts of entangled centimeter-long filamentous bacteria. "Before us nobody had hypothesized
about its existence, so nobody had looked for it" says Risgaard-Petersen.

The filaments of bacteria stretch between the top and bottom sediment layers (Credit: Nils Risgaard-Petersen)

The filamentous microbes
turned out to be new members of the Desulfobulbaceae family, which includes
bacteria capable of consuming hydrogen sulfide in deep sediment zones. This
seemed like a good indication that these long bacteria filaments could be
mediating the flow of electrons across distant sediment layers. Indeed, when
the scientists cut the filaments, the electric currents stopped and the
consumption of oxygen and hydrogen sulfide plunged.

"Risgaard-Petersen
and collaborators linked the presence of bacterial filaments to the electrical
coupling of the oxygen and sulfide layers in marine sediments, which are
typically separated by millimeter to centimeter distances" says Gemma Reguera, a microbiologist from
Michigan State University specialized in the study of sediment bacteria "These [distance] scales truly defy
our current knowledge of biological electron transfer".

Each filament consists of
many bacterial cells lined up in a long chain and surrounded by a shared outer
membrane. Interestingly, this outer membrane has uniform ridges filled up with
charged material running along the entire length of the filament. The authors
of the study believe these ridges could be 'internal insulated wires' for
driving the electron flow across sediment layers. However, these molecular
details remain unclear.

A cross-section of four cable bacteria viewed with an transmission electron microscope (Credit: Karen Thomsen)

Derek Lovley, an expert
on electromicrobiology at the University of Massachusetts thinks that
discovering the source of this 'potentially conductive material' is crucial. "As with the initial studies with
[bacterial nanowires] there will be skeptics because they have not been able to
measure long-range electron transport directly" and adds "It will be
interesting to watch this story unfold."

More
than tens of thousand kilometers of filamentous bacteria live in a single
square meter of mud from the undisturbed seabed, so it is possible that this
type of long-distance electron transport could be widespread in nature. The
long filaments are however very fragile, and small disturbances such as sea
waves could lead to 'fatal cable breakage'. Eric Roden, an expert on
biogeochemistry at the University of Wisconsin notes "Whether
or not such filamentous networks are actually present and active in natural
sediments, where all sorts of mixing processes and other disturbances are
common, remains to be determined".

Since
the discovery of bacterial nanowires, several research teams have explored
their potential biotechnological applications, for example, in bioelectronic
devices or for electricity generation from renewable sources, such as waste.
Could the filamentous bacteria potentially be used for technology development?

"We need to know more about how current is
transported inside these organisms" explains Risgaard-Petersen "but
perhaps there is a possibility to grow electric conductive structures for use
in electrical devices".

This article was published in The Munich Eye on 26-10-2012. You can read it here.

13 Nov 2012

Parents may have found a new reason to
encourage their children to play a musical instrument. A new study led by
scientists at Northwestern University reports that musical training during
childhood can have positive effects on the adult brain, even if the training
only lasts a few years.

Credit: everystockphoto

As children return to school, many parents
face the question of whether to enroll their child in music lessons. They don't
want to overload their child with extracurricular activities, but they are also
afraid of missing the age window when musical talent can be discovered and
nurtured. Besides, an investment in music lessons might be fruitless if the
child stops playing the musical instrument at a later age. Yet scientists now
argue this is not the case.

Research on professional musicians shows that
musical experience can not only rewire the auditory system, but also improve
several of the brain's functions, such as motor control, memory and verbal
ability. However, it had never been investigated whether these positive changes
in the brain persist if the musical training stops before adulthood, which is
indeed the case for most people who engage in music lessons at a young
age.

In a new study published in August in the
Journal of Neuroscience, scientists test healthy adults who started playing a
musical instrument at around 9 years of age but stopped a few years later. They
used a technique called Auditory Brainstem Response (ABR), which measures brain
activity after auditory stimulation, a similar test to the one used to assess
whether newborn babies can hear. The scientists then performed the same
experiments on adults who have never played an instrument and compared the
results.

'We find that the adult brain profits from past experiences with
music. This is the first study to focus on whether the effects of music are
long-lasting and whether they persist after the child stops playing an
instrument' explains Erika Skoe, leading author in the study.

The authors of the study propose that these
long-term positive changes in the brain could be a result of the active
interaction with sound that occurs when playing a musical instrument. 'Playing a musical instrument is an incredibly active process that engages
all of the senses, not just hearing. Active engagement with sound appears to be
the critical ingredient for promoting long-lasting neural changes' says
Skoe. This could explain why passive exposure to an enriched auditory
environment alone only produces a temporary enhancement of brain activity, a
phenomenon that has been observed in rat models. Referring to these experiments
Skoe explains 'An enriched auditory environment was more or less "background
music" in the animal's environment and not something that they could
directly interact with.'

So when should children start learning music
in order to benefit from these long-lasting neural changes?

'Our study suggests that long-lasting
effects can be seen with just one year of music lessons during grade [primary]
school. However, music is likely to be a positive force on the brain at any
age. Because every child is different, we are cautious about interpreting our
results too prescriptively' answers Skoe.

This and other studies raise the debate of
whether or not music lessons should be compulsory in state schools. Nina Kraus,
head of the Auditory Neuroscience Laboratory where the present study was
conducted says

From this elegant research we learn that
playing a musical instrument during childhood has long-lasting positive effects
on the brain. And the good news for parents is, that children will benefit from
their music lessons throughout their adult life, even if they decide to swap
the violin for a surfboard in their teens.

This article was published in The Munich Eye on 7-10-2012. You can read ithere.

9 Nov 2012

Scientists used a microchip that recreates a
breathing lung to study pulmonary edema and test a new drug against this
life-threatening disease, raising hopes that this organ-on-chip technology
could speed up drug development and replace animal testing.

The lung-on-a-chip is the size of a memory stick and is made of a clear silicone rubber (credit: Harvard University Wyss Institute)

The lung-on-a-chip was first developed by Donald Ingber's team at the Harvard University Wyss Institute two years ago using technology from the computer microchip industry. The microdevice mimics the tiny air sacs in the lungs where gases are exchanged between the air
we breathe and the blood.

About the size of a memory stick, the plastic microchip contains two chambers
separated by a thin leaky membrane. This flexible membrane has living lung
cells with air flowing through them stuck on one side, and blood vessel cells
immersed in fluid on the other. Gases or fluids can be transferred across the
membrane between lung and blood vessel tissues.

The membrane and attached cells are stretched and relaxed by a vacuum system in
the same way as an air sac during breathing movements.

Now, in a study published this week inScience Translational Medicine, the
Harvard scientists used these microchips to mimic pulmonary edema, showing for
the first time that organs-on-chip can be used to model human disease.

Pulmonary edema is the abnormal buildup of fluid in the lung air sacs, which
leads to respiratory failure and if left untreated can be fatal. The most
common cause of pulmonary edema is congenital heart failure, but it can also
occur as a side effect of some drugs.

In this study, the researchers usedinterleukin-2(IL-2), a chemotherapy drug with
severe side effects, to recapitulate pulmonary edema in the lung-on-a-chip. Injection of this drug into the microchip blood chamber triggered fluid leakage
across the membrane into the air space, recreating what happens in the lungs
of human patients treated with IL-2.

But there was a surprising result: the physical action of 'breathing'
aggravated fluid leakage into the air chamber. IL-2 causes cell connections to
break, which opens holes in the tissues. It turns out that the mechanical
strain of the breathing motion dramatically increases the size of these holes.
'This truly changes the way we view this disease process, as well as how we
might treat this type of condition' says Ingber.

This unexpected finding led the team to test an experimental drug developed by
GlaxoSmithKline (GSK) which blocks a protein involved in controlling tissue
mechanical tension. They found that the drug 'fully prevents the IL2-induced
edema response'. In a collaborative study, a GSK research team led by Kevin
Thorneloe showed that the drug curbed pulmonary edema symptoms caused by heart
failure in animal models, confirming the lung-on-a-chip results.

Drug development is a long and costly process that currently relies on animal
testing, and more often than not drugs that perform well in animal models then
fail in the human clinical trial stages.

'Major pharmaceutical companies and government funding agencies are now
beginning to recognize a crucial need for new technologies that can quickly and
reliably predict drug safety and efficacy in humans in preclinical studies'
says Ingber.

Human cells cultured in a three-dimensional matrix are widely used to test drug
toxicity but they lack the complex properties that define organs, such as
tissue-tissue interactions or mechanically active environments. Organs-on-chip
could be the solution to this problem.

'Our finding that breathing motions are critical to mimic the IL-2 toxicity
response is a clear example of how this could not be done with conventional
culture models' says Ingber.

In the past years several groups have built organ-on-chips that mimic lung,
kidney, heart and other organs, but this study is the first to model a human
disease and to successfully test a drug in a microchip. Shuichi Takayama, an
expert on biomedical engineering at the University of Michigan says

'This study demonstrates that this type of technology is promising for
replacing animal models in some aspects of drug screening and testing.'

However, the organ-on-chip technology is in its early stages and Ingber believes
'animal models will be around for a long time'.

'The goal is to develop organ chip replacements
for one particular animal model at a time, and hence, slowly shift the emphasis
away from animal models. This would represent a major advance in the pharmaceutical
field, and have great implications for testing of chemicals, toxins and
cosmetics as well' he says.

This article was published in The Munich Eye on the 9-11-2012. You can read it here.

3 Nov 2012

New research shows that mating
with multiple partners brings benefits for females. In a study published in September in the journal BMC Evolutionary Biology, scientists report that promiscuous
female guppies are more fertile than singly mated females.

Female and male Trinidadian guppies(credit: Biodiversity and Behavioural Group at University of St Andrews)

For evolutionary biologists, it
is obvious why male promiscuity has selective advantages: mating with several
females gives males more chances to fertilize eggs and produce viable
descendants. However, female promiscuity, or polyandry (poly- many, andras-
male), still stirs a debate in the scientific community, because it doesn't
bring any apparent benefit for the females. On the contrary, multiple mating
can come at a high cost. Besides consuming time and energy, multiple mating
exposes females to predation, disease and physical harm from males. Female
polyandry is nonetheless widespread in nature, and growing evidence shows that
choosing to mate with several partners seems to be the rule, rather than the
exception in a wide number of species, from invertebrates to birds, reptiles
and even some mammals.

So why do females prefer to mate
with multiple males? Scientists believe that polyandry might have indirect
genetic benefits for the females, ensuring the 'good genes' pass on to the next
generation. For instance, in some species the offspring of promiscuous females
is better adapted, and hence produces more grandchildren for the female, than
ofspring from single mated females. However, in the study performed by Anne
Magurran's team at the University of St Andrews in the UK, the researchers
found that, unexpectedly, multiple mating brings direct benefits for females.

The scientists performed
controlled experiments in the laboratory with wild caught guppies from the
Lower Tacarigua River in Trinidad. They placed about 80 females in individual
tanks and then allowed them to mate either with a single male, or with multiple
males. They carefully followed these guppies for two generations, keeping count
of the number of children and grandchildren they produced. They found that
promiscuous females had more offspring, but there was no difference in their
size, growth rate or viability, when compared to offspring of single mated
females. Miguel Barbosa who led the study says 'The surprise came when the results
showed that the benefits of multiple mating were achieved through an increase
in female fecundity rather than by increasing offspring
viability/attractiveness, as expected.'

Previous research showed a
similar increase in fertility in promiscuous females of other species, but this
is the first study where both direct and indirect benefits of multiple mating
are investigated over two generations. But why is there an increase in
fertility in multiply mated females? Barbosa explains 'The presence of sperm
from multiple sources/fathers reduces the risk of genetic incompatibility, but
also promotes sperm competition. Both can contribute to the increase in
fecundity reported in our study.'

Another surprising finding in
this study was that promiscuous female guppies had more sons, and scientists
believe this accounts for the larger number of grandchildren. 'There was 60%
more sons produced by multiple mated females than produced by single mated
ones' says Barbosa. This is the first evidence that female multiple mating
influences the offspring sex-ratio in guppies, but the scientists, however,
still don't understand what causes this overproduction of males.

Tommaso Pizzari, an evolutionary
biologist from the University of Oxford in the UK, says 'The present study
offers experimental evidence suggesting that female promiscuity might be
associated with some net fitness benefits to the female (...) These results
contribute to shed light into a major evolutionary puzzle: namely, why do
females mate with multiple males when often one insemination is sufficient for
fertilization and mating is costly.'

This article was published in The Munich Eye on 02-10-2012. You can read it here.